Tizanidine hydrochloride) is a centrally acting α2-adrenergic agonist.
Tizanidine HCl (tizanidine) is a white to off-white, fine crystalline
powder, which is odorless or with a faint characteristic odor. Tizanidine is
slightly soluble in water and methanol; solubility in water decreases as the
pH increases. Its chemical name is
5-chloro-4-(2-imidazolin-2-ylamino)-2,1,3-benzothiodiazole
hydrochloride.tizanidine tablets are composed of the active
ingredient, tizanidine hydrochloride (2.29 mg equivalent to 2 mg tizanidine
base and 4.58 mg equivalent to 4 mg tizanidine base), and the inactive
ingredients, silicon dioxide colloidal, stearic acid, microcrystalline
cellulose and anhydrous lactose.

Tizanidine Hcl is a short-acting drug for the management of spasticity.
Tizanidine Hcl is an agonist at a2-adrenergic receptor sites and presumably
reduces spasticity by increasing presynaptic inhibition of motor neurons. In
animal models, tizanidine has no direct effect on skeletal muscle fibers or
the neuromuscular junction, and no major effect on monosynaptic spinal
reflexes. The effects of tizanidine are greatest on polysynaptic pathways.
The overall effect of these actions is thought to reduce facilitation of
spinal motor neurons.